1. Field of the Invention
This invention relates to an improved mechanical mineral beneficiation apparatus and process, and is more particularly concerned with a method and apparatus which concentrates the heavier constituents of particulate material without having to additionally separate the particulate material from a fluvial transport within a configuration in which the expansion of the apparatus for the purpose of increasing unit capacity is not inseparably tied to factors which, upon such expansion, adversely affect the stratification portion of the process.
2. Description of the Prior Art
Mineral beneficiation, and particularly classification of particulate material according to relative weight, was greatly improved by the Apparatus and Process for Ordinary and Submarine Mineral Beneficiation, as disclosed in my U.S. Pat. No. 4,120,783. The method and apparatus disclosed in the '783 patent eliminated many of the disadvantages of the prior art devices such as tables, and undercut sluice types such as the spiral, the cone, the Lamflo concentrator and the undercut sluice tray by, inter alia, providing a closed chamber for the introduction of a slurry of the particulate material. The '783 patent eliminated the unbroken common flow path of the particulate matter and fluid carrier, present in prior devices, which necessitates a flow velocity sufficient to transport the full range of particle sizes in the slurry, and thus substantially eliminated the resulting hydrologic equilibrium that occurs in a fluvial transport between particles of different specific gravities because of their sizes and shapes. Other advantages included the elimination of a fixed enrichment ratio; the elimination of restrictive-common-adjustments affecting more than one function; the elimination of any middlings product; the elimination of feed density as a factor in process efficiency; the elimination of slurry flow rate as a factor in process efficiency; and the elimination of surface tension and its negative effect on mechanical mineral processing. Other advantages of the '783 patent included providing a means to control exposure time of particulate matter through the stratification portion of the process. It also provided a means to accommodate both barren ore and ore "hot spots" with a floating enrichment-ratio that automatically responds to changing ore conditions, and it also provided a means to monitor, program and automatically control the entire process. The method and apparatus disclosed in the '783 patent, however, included many limitations. In that device, a slurry is introduced into the housing against a baffle that directed the slurry outwardly against the housing. The slurry is then passed through various separation zones. Therefore, the particulate material feed and flow path is combined with the fluid and fluid flow path through a substantial portion of the process circuit. Because of this, hydrologic equilibrium can still occur, although to a far lesser degree than in prior art devices. The result of the hydrologic equilibrium effect is a non-linear recovery of the valuable constituents caused by the relatively finer valuable particles being held in suspension and flushed through the process circuit in the fluvial transport and thus lost in the waste product. Further, the process of the '783 patent necessitates that the particulate matter ultimately be separated from its fluvial transport. Another important limitation of the device and its process is that the area of highest concentration of the desired product (the valuable constituents) is not coordinated with the point of discharge for this product. This is because the lowest point of the stratification zone and the point of discharge are toward the center of the housing, and away from its periphery, therefore the centrifugal forces generated by the oscillation of the housing tends to move the heavier concentrate away from the housing center and generally adversely affects the process. With the invention herein disclosed, the centrifugal forces are utilized to enhance the separation and stratification process having placed the lowest point of the stratification zones and the point of concentrates discharge at the periphery of the process housing. Finally, and one of the more serious limitations to commercializing the process of the '783 patent is in that configuration the angles and the depth that define the stratification zone, which are critical factors for efficient mechanical separation, are inseparably tied to, and change with the expansion of the process housing which is necessary for increasing unit capacity. With the present invention there are multiple stratification zones located at the periphery of the process housing which can be incorporated in any number required to meet any desired unit capacity, each designed with optimum depth and angles independent of the size of the process housing.